Journal of Powder Materials

Technology Trend of Powder-Metallurgical Aluminum Parts: Jae-Wook Lee, Sang-Sun Yang, Yong-Jin Kim; J Korean Powder Metall Inst. 2007;14(6):339-347.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.339

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Application of PM to the Consolidation of Metallic Glassy Powder and its Composites: Su-Min Shin, Taek-Soo Kim, Jin-Kyu Lee, Min-Seok Song, Jeong-Gon Kim; J Korean Powder Metall Inst. 2007;14(6):348-353.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.348

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Abstract PDF: In the present study, Zr-base metallic glass (MG) and Zr-base BMG/diamond composites were fabricated using a combination of gas atomization and spark plasma sintering (SPS). The microstructure, thermal stability and mechanical property of both the specimens as atomized and sintered were investigated. The experimental results showed that the SPSed specimens could be densified into nearly 100% and maintained the initial thermal stability at the sintering temperature of 630K. In addition, MG/diamond powder composites were successfully synthesised using SPS process. The composites, even a very low diamond volume fraction, generated a significant increase in compressive strength. With increasing the diamond volume fraction, the compressive strength was also increased due to the addition of hardest diamonds. It suggests that these composites would be potential candidates for a new cutting tool material.

Bi-materials of Al-Mg Alloy Reinforced with/without SiC and Al₂O₃ Particles; Processing and Mechanical Properties: Si-Young Chang, Han-Gyoung Cho, Yang-Do Kim; J Korean Powder Metall Inst. 2007;14(6):354-361.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.354

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The bi-materials with Al-Mg alloy and its composites reinforced with SiC and Al_2O_3 particles were prepared by conventional powder metallurgy method. The A1-5 wt%Mg and composite mixtures were compacted under 150sim450;MPa, and then the mixtures compacted under 400 MPa were sintered at 773sim1173K for 5h. The obtained bi-materials with Al-Mg/SiCp composite showed the higher relative density than those with Al-Mg/Al_2O_3 composite after compaction and sintering. Based on the results, the bi-materials compacted under 400 MPa and sintered at 873K for 5h were used for mechanical tests. In the composite side of bi-materials, the SiC particles were densely distributed compared to the Al_2O_3 particles. The bi-materials with Al-Mg/SiC composite showed the higher micro-hardness than those with Al-Mg/Al_2O_3 composite. The mechanical properties were evaluated by the compressive test. The bi-materials revealed almost the same value of 0.2% proof stress with Al-Mg alloy. Their compressive strength was lower than that of Al-Mg alloy. Moreover, impact absorbed energy of bi-materials was smaller than that of composite. However, the bi-materials with Al-Mg/SiCp composite particularly showed almost similar impact absorbed energy to Al-Mg/Al_2O_3 composite. From the observation of microstructure, it was deduced that the bi-materials was preferentially fractured through micro-interface between matrix and composite in the vicinity of macro-interface.

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Effect of Heat Treatment on Microstructure and Mechanical Properties of Electromagnetic Duo-Cast Al Hybrid Material
Jun Young Suh, Sung Jin Park, Do-Kyun Kwon, Si Young Chang
Korean Journal of Materials Research.2018; 28(9): 499. CrossRef
Microstructure and Mechanical Behavior of Al-Mg-Si/Al Hybrid Alloy by Duo-casting
Ji-Min Han, Chong-Ho Kim, Jun-Pyo Park, Si Young Chang
Journal of the Korea Foundry Society.2012; 32(6): 269. CrossRef
Microstructure and Tensile Properties of Al-Mn/Al-Si Hybrid Aluminum Alloy Prepared by Electromagnetic Duo-Casting
Sung-Jin Park, Tingju Li, Chong-Ho Kim, Jun-Pyo Park, Si-Young Chang
Korean Journal of Materials Research.2012; 22(2): 97. CrossRef

Densification Behaviour of Magnesium Powders during Cold Isostatic Pressing using the Finite Element Method: Seung-Chae Yoon, Eun-Jeong Kwak, Won-Hyoung Choi, Hyoung-Kun Kim, Taek-Soo Kim, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2007;14(6):362-366.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.362

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Magnesium and magnesium alloys are promising materials for light weight and high strength applications. In order to obtain homogeneous and high quality products in powder compaction and powder forging processes, it is very important to control density and density distributions in powder compacts. In this study, a model for densification of metallic powder is proposed for pure magnesium. The mode] considers the effect of powder characteristics using a pressure-dependent critical density yield criterion. Also with the new model, it was possible to obtain reasonable physical properties of pure magnesium powder using cold iso-state pressing. The proposed densification model was implemented into the finite element method code. The finite element analysis was applied to simulating die compaction of pure magnesium powders in order to investigate the density and effective strain distributions at room temperature.

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Analysis of Densification Behavior of Magnesium Powders in Extrusion using the Critical Relative Density Model
Seung-Chae Yoon, Hong-Jun Chae, Taek-Soo Kim, Hyoung-Seop Kim
Journal of Korean Powder Metallurgy Institute.2009; 16(1): 50. CrossRef
Finite element analysis of the bending behavior of a workpiece in equal channel angular pressing
Seung Chae Yoon, Anumalasetty Venkata Nagasekhar, Hyoung Seop Kim
Metals and Materials International.2009; 15(2): 215. CrossRef

Life and Mechanical Properties of Hot Former Die for Bearing Race using P/M High Speed Steel: Seong-Hyeon Hong, Jong-Soo Bae; J Korean Powder Metall Inst. 2007;14(6):367-371.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.367

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Abstract PDF: P/M high speed steel (1.26% C, 4.42% Cr, 6.54% W, 4.92% Mo, 3.21 % V, 8.77% Co, bal. Fe) was applied to hot former die. It showed that the die life became 2.7 times higher than that of cast/wrought SKH 55 tool steel which is commercially used. The increase of die life was corresponding to the improved hardness and transverse rupture strength of PM high speed steel due to the finer grain and carbide as well as the uniform carbide distribution. The P/M high speed steel with the promoted die life could be an alternative to the conventional SKH55.

Characteristics of Plasma Electrolytic Oxidation Coatings on Mg-Zn-Y Alloys Prepared by Gas Atomization: Si-Young Chang, Han-Gyoung Cho, Du-Hyung Lee, Taek-Soo Kim; J Korean Powder Metall Inst. 2007;14(6):372-379.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.372

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The microstructure, mechanical and electrochemical properties of plasma electrolytic coatings (PEO) coatings on Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn-2.0 wt%Y alloys prepared by gas atomization, followed by compaction at 320 for 10 min under the pressure of 700 MPa and sintering at 380 and 420 respectively for 24 h, were investigated, which was compared with the cast Mg-1.0 wt%Zn alloy. All coatings consisting of MgO and Mg_2SiO_4 oxides showed porous and coarse surface features with some volcano top-like pores distributed disorderly and cracks between pores. In particular, the surface of coatings on Mg-1.0 wt%Zn-2.0 wt%Y alloy showed smaller area of pores and cracks compared to the Mg-4.3 wt%Zn-1.0 wt%Y and Mg-1.0 wt%Zn alloys. The cross section micro-hardness of coatings on the gas atomized Mg-Zn-Y alloys was higher than that on the cast Mg-1.0 wt%Zn alloy. Additionally, the coated Mg-1.0 wt%Zn-2.0 wt%Y alloy exhibited the best corrosion resistance in 3.5%NaCl solution. It could be concluded that the addition of Y has a beneficial effect on the formation of protective and hard coatings on Mg alloys by plasma electrolytic oxidation treatment.

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The Aging Characteristics of Mg-6 wt.% Al-1 wt.% Zn Alloy Prepared by Gas Atomization
Du-Hyung Lee, Bo-Sik Kim, Si-Young Chang
Journal of Korean Powder Metallurgy Institute.2009; 16(4): 275. CrossRef

Magnetic Pulsed Compaction and Sintering Characteristics of Al Composite Powders Reinforced with Waste Stainless Steel Short Fibers: Chang-Yong Hyun, Chul-Hyun Won, Jae-Soon Park; J Korean Powder Metall Inst. 2007;14(6):380-385.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.380

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Abstract PDF: Characteristics of Al-based composites with waste stainless steel short fiber, fabricated by magnetic pulsed compaction and sintering were investigated. The compacts prepared by magnetic pulsed compaction showed high relative density and homogeneous microstructure compared with that by conventional press compaction. The relative density of sintered composites at 430°C for 1 h exhibited the same value with compacts and decreased with increase in STS short fiber content. The reaction between Al and STS phase was confirmed by the microstructural analysis using EDS. The sintered composites, prepared by magnetic pulsed compaction, showed increased hardness value with increasing STS fiber content. Maximum yield strength of 100 MPa and tensile strength of 232 MPa were registered in the AI-based composite with 30 vol% STS short fiber.

Sintering Behavior and Mechanical Property of Mo Nanopowders: Hai-Gon Kim, Gil-Su Kim, Sung-Tag Oh, Myung-Jin Suk, Young-Do Kim; J Korean Powder Metall Inst. 2007;14(6):386-390.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.386

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Abstract PDF: The sintering behavior and mechanical property of Mo nanopowder was investigated as a function of various sintering condition. Mo oxide nanopowders were milled using a high energy ball-milling process. After the ball milling for 20h, the crystalline size of MoO_3 was about 20 nm. The MoO_3 nanopowders were reduced at the temperature of 800°C without holding time in H_2 atmosphere. The sinterability of Mo nanopowder and commercial Mo powder was investigated by dilatometric analysis. Mo nanopowder and commercial Mo powder were sintered at 1200°C for 1 hand 1500°C for 3 h, respectively. In both specimens the measured relative density was about 95%. But the measured hardness values were 2.34 GPa for nanopowder and 1.87 GPa for commercial powder. Probably due to finer grain size of the sintered body prepared from Mo nanopowder than that prepared using commercial Mo powder. The mean grain sizes were measured to be about 1.4 mm and 6.2 mm, respectively.

Determination of Fractal Dimension and Surface Characterization of Metal Nano-powder Using Nitrogen Gas Adsorption Method: Gyoung-Ja Lee, Young-Rang Uhm, Chang-Kyu Rhee; J Korean Powder Metall Inst. 2007;14(6):391-398.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.391

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The surface roughness of Al, Ag and Ni nano-powders which were prepared by pulsed wire evaporation method was quantified based upon the fractal theory. The surface fractal dimensions of metal nano-powders were determined from the linear relationship between In V/V_mono and Inln (Po/P) using multi-layer gas adsorption theory. Moreover, the fractal surface image was realized by computer simulation. The relationship between preparation condition and surface characteristics of metal nano-powders was discussed in detail.

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Electrophoretic deposition of Ni nanoparticles from suspension on to a Ni plate
Keun-Yong Park, Young Rang Uhm, Kwang Jae Son, Deok-Yong Park
Research on Chemical Intermediates.2015; 41(9): 6721. CrossRef

Consolidation and Characterization of Cu-based Bulk Metallic Glass Composites: Jin-Kyu Lee, Taek-Soo Kim; J Korean Powder Metall Inst. 2007;14(6):399-404.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.399

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Abstract PDF: The Cu-based bulk metallic glass (BMG) composite was fabricated by spark plasma sintering (SPS) using of gas-atomized metallic glass powders and ductile brass powders. No defect such as pores and cavities was observed at the interface between the brass powder and the metallic glass matrix, suggesting that the SPS process caused a severe viscous flow of the metallic glass and brass phases in the supercooled liquid region, resulting in a full densification. The BMG composites shows some macroscopic plasticity after yielding, although the levels of strength decreased.

Fabrication of Metallic Glass/metallic Glass Composites by Spark Plasma Sintering: Jin-Kyu Lee; J Korean Powder Metall Inst. 2007;14(6):405-409.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.405

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Abstract PDF: The Cu-based bulk metallic glass (BMG) composites containing Zr-based metallic glass phase have been consolidated by spark plasma sintering using the mixture of Cu-based and Zr-based metallic glass powders in their overlapped supercooled liquid region. The Zr-based metallic glass phases are well distributed homogeneously in the Cu-based metallic glass matrix after consolidation process. The successful consolidation of BMG composites with dual amorphous phases was corresponding to the sound viscous flow of the two kinds of metallic glass powders in their overlapped supercooled liquid region.

Measurement Uncertainty for Analysis of Residual Carbon in a Tungsten-15% Copper MIM part: Jeong-Keun Lee; J Korean Powder Metall Inst. 2007;14(6):410-414.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.410

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Abstract PDF: Carbon contamination from the binder resin is an inherent problem with the metal powder injection molding process. Residual carbon in the W-Cu compacts has a strong impact on the thermal and electric properties. In this study, uncertainty was quantified to evaluate determination of carbon in a W-15%Cu MIM body by the combustition method. For a valid generalization about this evaluation, uncertainty scheme applied even to the repeatability as well as the uncertainty sources of each analyse step and quality appraisal sources. As a result, the concentration of carbon in the W-Cu part were measured as 0.062% with expanded uncertainty of 0.003% at 95% level. This evaluation example may be useful to uncertainty evaluation for other MIM products.

화염법을 이용한 나노입자의 제조 동향 및 전망: Sang-Seon Yang, Jae-Uk Lee, Yong-Jin Kim; J Korean Powder Metall Inst. 2007;14(6):415-421.; DOI: https://doi.org/10.4150/KPMI.2007.14.6.415

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